Modern developments in electricity production have produced an increased requirement for energy storage. Many forms of renewable energy, such as wind turbines and photoelectric solar systems, produce energy in a variable fashion. For example, wind turbines may produce relatively large amounts of power when the wind is locally suitable, and produce nothing when the wind stops.
This may be compensated for in the grid as a whole by factors such as variable load demands, geographical diversity of wind generators, and accessing alternative generators. However, this does not allow the wind generator to controllably deliver power when the price is optimised. Further, there is no ability to smooth the power output even over a time frame of minutes, so that it is difficult for the grid operator to provide properly regulated power, especially given that the wind generator may be remotely positioned on the grid relative to the bulk of electricity consumers.
Energy storage systems of various kinds have accordingly come into wider consideration, so that outputs can be smoothed, or even stored for later re-sale or use. Energy storage battery arrays, typically may be utilized in such energy storage systems associated with renewable energy production.
Such arrays may, in one form, consist of several hundred lead acid batteries. The battery array is generally contained in structures or cabinets. In a larger installation, the batteries may be arranged in groups of 20 or so, called strings, which are connected to provide the overall facility.
The operation of the array necessarily generates heat, during charging and discharging in particular. The operating life of lead acid batteries is directly related to the temperature in which they operate. In particular, increasing the operating temperature for lead acid batteries tends to increase the corrosion of the positive grid. Similar negative effects exist for other battery technologies. Thus, in such arrays, careful attention is required to temperature management.
One approach is to provide active cooling, using air conditioning, heat exchangers, and associated fans. However, such cooling is effectively a parasitic load on the storage system, as it then requires additional battery capacity to be provided in order to operate the cooling system. Further, such an approach necessarily increases capital cost, and reduces the efficiency and effectiveness of the storage system.
Another important constraint is footprint. If the batteries could be spaced an arbitrarily large distance apart, then the issue of cooling could be readily resolved. However, in real world installations, floor space is a limited resource. Additional considerations of the length (and hence cost) of connections between batteries, safety, protection of the batteries and avoiding trip hazards make such solutions impractical.
It is an object of the present invention to provide an arrangement for a battery array which reduces (or eliminates) the requirement for active cooling, while improving the cost effectiveness of the storage system.